Yamaha T-85 Fm tuner mods.

[pdul]

Has anybody tried to mod the audio part of a Yamaha T-85 tuner
from 86?
My plan was initialy to just recap. the whole unit, but after opening it a very nice layout was looking at me saying MOOOOD. As a start maybe replacing some audio opamps
NJM2041S and NJM2043S with some LME49720.
Any comments to that?

[planet10]

Gregg the Geek added a tube analog stage to my T-460 (and blue LEDs). I've been happily using it for the last couple years.

dave

[pdul]

It sounds to me like a much bigger project, new power supply, holes for tubes etc. Not really what i had in mind.
The sonic quality of the gismo is already surprisingly good, so i think that something like new faster and more precise opamps
will do and maybe due to lower offset (new opamps) some experiments with replacing some BP caps in the signal path with some one point second order dc servos.
comments are welcome.

[grenert]

Is your tuner aligned? I had my T-85 aligned by a tuner expert, along with putting in matched filters and Black Gate output capacitors. I am convinced it was the alignment that did the most good. The specifications were remarkably better following alignment.

[pdul]

All i can say is that it is the most precise and noiseless tuner i have had yet and normally i would have been more than satisfied
with its current soundquality if not for my itchy diy fingers and the discovery of opamps with a slew rate of 3v/uS and caps in the signalpath

[pdul]

Hi! I am now back again with my latest changes/improvements of my tuner.
First i have replaced all the electrolytics:
power supply: Rifa 105C and Panasonic FM
Everything else Panasonic FC and Rubycon YXF, Other than that i have replaced the opamps in the audio section with some browndogs SIP-DIL8 and for now i have put some OP275 i had at hand instead of the original NJM2041S and i must say that i have a big improvement in sound quality ofcourse subjective to my ears but anyway a big change.
I forgot to mention that the 4,7uf output caps has been replaced with two 10uf SILMIC face to face instead of the original standard BP Nichicons.
Knowing that OP275 is not axactly state of the art opamps, maybe somebody can suggest something else with transparancy as the target?
Or maybe further modifications?

Sorry for my rusty english

[pdul]

Hi again i have now made a local decoupling of the rails which are +- 12v for the opamps with 56uf panasonic FC + 220NF Siemens MKT

[rwidebrook]

Late addition, but mining these older threads are DIYer's gold! I also wanted to try improving my T-85; it was nice, but a friend's modded Sony tuner still vastly topped it for FM sound quality. Replaced main caps in the power supply and MPX decoder sections with Silmic IIs and BlackGates; replaced the 4.7uf output coupling caps with Aerovox film caps. That helped the bass definition and overall sound, but not the air/reality/soundstage that were missing. Then the challenge: the audio opamp in PCB position IC210 was a 9-pin SIL NJM2041S; cursory research indicated an LM4562 would be a nice upgrade, but how to fit an 8-pin DIP to that 25-year-old 9-pin SIL position?

Ordered a BrownDog Model 060301 adapter (converts 8-pin DIP to 9-pin SIL) from Cimarron Technology, Inc.. Desoldered and pulled the NJM2041S, fitted the LM4562 to the adapter and soldered the adapter's 8-pins to the PCB's IC210 SIL pins 2 thru 9, then soldered a jumper wire between the IC210 position's pin 1 to pin 9 (since 9-pin SIL opamps duplicate V+ on those pins). Crossed fingers and hooked it up.

VoilaX2! After 15 minutes of break-in time, the air and soundstage blossomed; resolution increased; tone improved. I can highly recommend the LM4562 + BrownDog adapter for the Yamaha T-85: really elevate its audiophile qualities. But, while removing the NJM2041 SIL: careful with that soldering iron, Eugene.